Re: builtin printf behaves incorrectly with "c and 'c character-value arguments

[Chet Ramey]

Rich Felker wrote:
> $ printf %d\\n \'À
> -61
> (expected 192)
> 
> This should be 192 regardless of locale on any system where wchar_t
> values are ISO-10646/Unicode. Bash is incorrectly reading the first
> byte of the UTF-8 which happens to be -61 when interpreted as signed
> char; on a Latin-1 based locale it will probably give -63 instead.
> 
> Both POSIX and common sense are clear that the numeric values
> resulting from 'c should be the wchar_t value of c and not the value
> of the first byte of the multibyte character; from the SUSv3 printf(1)
> documentation:
> 
>      Note that in a locale with multi-byte characters, the value of a
>      character is intended to be the value of the equivalent of the
>      wchar_t representation of the character as described in the
>      System Interfaces volume of IEEE Std 1003.1-2001.
> 
> Language lawyers could argue that on 'single-byte' locales perhaps the
> byte value should be used; however, strictly speaking a single-byte
> locale is simply a special case of a multi-byte one, and sanity should
> win in any case.

You're correct that the bash printf should understand multibyte characters
in a multibyte locale, but not that returning a multibyte character when
a user hasn't asked for one by setting the locale is more "sane."

Chet
-- 
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Chet Ramey, ITS, CWRU    chet@case.edu    http://cnswww.cns.cwru.edu/~chet/